Lecture Notes

Question 1

Pyroxene Formula

Answer 1

XYSi2O6
X=larger cation Na, Ca, Mn, Fe, Mg, Li
and Y=smaller cation Mn, Fe, Mg, Al

Question 2

What is the cathode in x-ray diffraction

Answer 2

Tungsten fillament.

It is heated, and it lightens up from electron being emitted.

Question 3

Constructive vs. destructive interference

Answer 3

Constructive is when 2 waves are n’sync with one another and combine and the aptitude is magnified. Destructive is when 2 waves are combined and their amplitude is dampened.

Question 4

Debye-Scherger Method

Answer 4

Grind up the unknown mineral. Put specimen in capillary tube, many grains. *randomize the grains. Shoot x-rays at it pew-pew-pew

Question 5

Phyllosilicates

Answer 5

Sheet Silicates
Si2O5
Platy, flaky, soft, flexible, and elastic.

Question 6

orthosilicates

Answer 6

Compounds with isolated SiO4 tetrahedra (no sharing of tetrahedral corners with other tetrahedra)

Question 7

Shielding

Answer 7

If you have a charge on a cation and they are sitting near each other with an oxygen in between they don’t see each other -A matter of relative stability

Question 8

Shared edges are always _______.

Unshared edges are always _______.

Answer 8

short/long

Question 9

If the site energy is different what can you expect to happen?

Answer 9

cations to separate

note this doesn’t happen in Olivine

Question 10

If you increase pressure you will _________ density.

Answer 10

increase. A higher pressure phase will tend to have an atomic arrangement with atoms closer together

Question 11

As you increase temperature you will ________ density.

Answer 11

Decrease. A higher temperature phase will tend to have an atomic arrangement with atoms further apart.

Question 12

Something you can use to recreate past temperatures.

Answer 12

geothermometer

Question 13

Something you can use to recreate past pressures

Answer 13

geobarometer

Question 14

planes

Answer 14

single sets of atoms arranged in two dimensions.

Question 15

tetrahedral sheet

Answer 15

corner sharing tetrahedra

Question 16

octahedral sheet

Answer 16

edge sharing tetrahedra. 2 types
trioctahedral (all 3 cations present)
dioctahedral sheet (2 of the 3 cations are present)

Question 17

Layer

Answer 17

A composite of sheets

Question 18

1:1 layer

Answer 18

One tetrahedra sheet plus one octahedral sheet

Question 19

2:1 layer

Answer 19

two tetrahedral plus one octahedral sheet

Question 20

6 varieties of layer silicates

Answer 20

Talc, Mica, Smectite, chlorite, 1:1, 2:1

Question 21

which expands more smectite or vermiculite?

Answer 21

smectite

Question 22

polytypism

Answer 22

A special type of polymorphism due to stacking in one direction

Question 23

Polytypes

Answer 23

To specify the structure.

Question 24

Tetrahedral/octahedral sheet misfit-increase the tetrahedral sheet

Answer 24

requires that the tetrahedral out of the plane tilts.

Question 25

Clay

Answer 25

A general term for fine grained material. Generally plastic with a limited amount of water and it will harden when dried or fired. Exact size requirements vary by discipline.

Question 26

How does a clay structure look if salt is not present?

Answer 26

Builds up like a stack of cards. Colloid framework.

Question 27

How does a clay look if salt is present?

Answer 27

Everything collapses “flocculation”

Question 28

Economic Importance of zeolites

Answer 28

molecular, drying, catalyst, exchange reactions